The results of preliminary studies in this laboratory using group housed mature stumptail macaques (M. arctoides) of both sexes demonstrated that the acute parenteral administration of d-amphetamine markedly alters interactive behavior patterns. These data suggest that the specific behavioral profile engendered depends on the dose, position of the treated subject in the dominance hierarchy of the group, sex, and the presence of concurrently treated subjects. The most conspicuous effect of treatment was an increase in presenting by the treated families which could possibly be interpreted as either an increase in submissive behavior or as an increase in sexual activity. The objectives of the proposed research program include a more detailed and objective assessment of the effects observed in the preliminary studies using the same species and testing apparatus. These broad objectives include a determination of (1) the effects of d-amphetamine on social behavior of the treated subject as well as on the behavior of untreated subjects toward the treated subject, (2) whether these effects are altered by the presence of other treated subjects (3) whether the sex and/or social position of the treated subject influence the effects of treatment (4) whether the treatment effects are dependent on the presence of untreated subjects of the opposite sex (5) whether these effects are qualitatively and/or quantitatively altered by chronic dosing, (6) whether treatment with d-amphetamine alters the dominance position of the treated subject as determined by a competition paradigm. Furthermore an operant behavioral paradigm (social avoidance, social reinforcement) will be utilized to more objectively assess the behavioral mechanisms of the observed changes in sexual and/or aggressive-submissive behaviors induced by d-amphetamine in the preliminary studies.